Hungry microbes share out the carbon in the roots...( Sugars made by plants are rapidly us...)

Sugars made by plants are rapidly used by microbes living in their roots, according to new research at the University of York, creating a short cut in the carbon cycle that is vital to life on earth.

The green leaves of plants use the energy of sunlight to make sugar by combining water with carbon dioxide from the atmosphere. This sugar fuels the plants growth, but scientists in the Universitys Department of Biology discovered that some of it goes straight to the roots to feed a surprising variety of microbes.

A study led by Professor Peter Young, of the Department of Biology at York and Dr Philippe Vandenkoornhuyse of the University of Rennes in France is published in the latest issue of the Proceedings of the National Academy of Sciences of the USA (PNAS).

In the carbon cycle, plants remove carbon dioxide (a greenhouse gas) from the atmosphere. Eventually, the carbon compounds that plants make are eaten by microbes and animals, which release carbon dioxide back into the atmosphere. The rapid cycling demonstrated by the new research is an important link in this process.

Professor Young said: Our research identifies microbes in roots that create a short cut in the carbon cycle. This is an important development given current interest in reducing outputs of carbon dioxide and the carbon trading that is intended to help this.

The researchers traced the path of the carbon by replacing the normal carbon dioxide in the air around the plants with a version made with C-13, a natural, non-radioactive form of carbon that is slightly heavier than the usual kind. Within hours, microbes in the roots were feeding on sugars laden with C-13 and using it to build their own cells.

The newly-made molecules of DNA and RNA produced by the microbes could be separated from pre-existing ones because the C13 made them heavier. DNA and RNA are large molecules that carry genetic information about the organisms that made them,
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